Method of mounting flexible circuit boards, and display device

ABSTRACT

The present invention is a method of mounting flexible circuit boards including: electrode groups formed on an insulating substrate; terminal groups formed in the vicinity of at least one side of the insulating substrate in such a manner as to be connected to outside at the electrode ends of the electrode groups; and terminals to be connected to the terminal groups; and a plurality of flexible circuit boards equipped with driver circuits for inputting signals to the electrode groups via the terminals, wherein the method includes the step of mounting the flexible circuit boards on the insulating substrate in a manner that the flexible circuit boards share overlap regions with adjacent flexible circuit boards.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. patent application Ser. No.10/292,167 filed Nov. 12, 2002 and from Japanese Application2001-357693, filed Nov. 22, 2001.

This application is also a continuation of U.S. patent application Ser.No. 10/292,167 filed Nov. 12, 2002, from which priority is claimed underall applicable sections of Title 35 of the United States Code including,but not limited to, Sections 120, 121, and 365 (c).

BACKGROUND OF INVENTION

The present invention relates to a method of mounting flexible circuitboards on a display device, which contains driver circuits mountedthereon, by using the flexible circuit boards, and more specificallyrelates to such a method suitable for a liquid crystal display device.

A method of mounting flexible circuit boards equipped with drivercircuits in a conventional display device has been disclosed in JapanesePatent Publication No. 3054135. FIG. 11 is a figure to explain a methodof mounting flexible circuit boards in the conventional art for liquidcrystal display device. In the view, reference numeral 1 shows aninsulating substrate, reference numeral 4 shows flexible circuit boards,reference numeral 5 shows driver circuits, and reference numeral 8 showscommon signal lines.

In FIG. 11, the common signal lines, which are commonly connected toeach driver circuit, are connected with the flexible circuit boards 4having the driver circuits on the insulating substrate 1 via an ACF(Anisotropic Conductive Film). As a result, the structure for providingthe common signal lines may become smaller, compared with theconventional structure where the common signal lines are formed on PCBs(Printed Circuit Boards) provided separately, thereby further making theframe area smaller in the display device.

However, the above-mentioned conventional art has the followingproblems. A problem is that it is necessary to form patterns on theinsulating substrate due to connecting the common signal lines 8 viapatterns 8. Another problem is that, in connecting the common signallines between two adjacent flexible circuit boards, two times as manyterminals as the number of the common signal lines are formed andconnected after the terminals of the flexible circuit board side and theterminals of the insulating substrate side are positioned, which makesit difficult to improve connection reliability. Further, another problemis that the flexible circuit boards are mounted at substantially thesame intervals on the insulating substrate as in each flexible circuitboard, which makes it difficult to achieve high density packaging thathas been demanded due to the high precision of the display devices inrecent years.

SUMMARY OF THE INVENTION

The present invention, which has been devised in view of theaforementioned problems, has as its objects to provide a method ofmounting flexible circuit boards that enables the flexible circuitboards to be mounted in high density and with high connectionreliability and to provide a display device containing such flexiblecircuit boards.

A first method of mounting flexible circuit boards of the presentinvention includes: electrode groups formed on an insulating substrate;terminal groups formed in the vicinity of at least one side of theinsulating substrate in such a manner as to be connected to outside atthe electrode ends of the electrode groups; and terminals to beconnected to the terminal groups; and a plurality of flexible circuitboards equipped with driver circuits for inputting signals to theelectrode groups via the terminals, the method including the step ofmounting the flexible circuit boards on the insulating substrate in sucha manner that the flexible circuit boards share overlap regions withadjacent flexible circuit boards.

A second method of mounting flexible circuit boards of the presentinvention is characterized in that, in the first method of mountingflexible circuit boards, the step of mounting the flexible circuitboards on the insulating substrate in such a manner that the flexiblecircuit boards share overlap regions with adjacent flexible circuitboards includes either the step of first mounting odd-numbered flexiblecircuit boards when counted from one end of the aligned flexible circuitboards, and then mounting even-numbered flexible circuit boards or thestep of first mounting even-numbered flexible circuit boards whencounted from one end of the aligned flexible circuit boards, and thenmounting odd-numbered flexible circuit boards.

A third method of mounting flexible circuit boards of the presentinvention is characterized in that, in the first or second method ofmounting flexible circuit boards, the flexible circuit boards furtherinclude driver signal lines which are coupled to outputs from the drivercircuits and are connected to the electrode groups on the insulatingsubstrate, and common signal lines which are connected between theflexible circuit boards, the method further including the step ofconnecting the common signal lines between adjacent flexible circuitboards through conductive patterns on the flexible circuit boards.

A fourth method of mounting flexible circuit boards of the presentinvention is characterized in that, in the third method of mountingflexible circuit boards, the step of mounting the flexible circuitboards on the insulating substrate in such a manner that the flexiblecircuit boards share overlap regions with adjacent flexible circuitboards further includes the step of connecting the common signal linesin regions where adjacent flexible circuit boards overlap with eachother and said adjacent flexible circuit boards also overlap with thesurface of the insulating substrate that has the electrode groupsthereon.

A fifth method of mounting flexible circuit boards of the presentinvention includes: electrode groups formed on an insulating substrate;terminal groups formed in the vicinity of at least one side of theinsulating substrate in such a manner as to be connected to outside atthe electrode ends of the electrode groups; and a plurality of flexiblecircuit boards equipped with driver circuits containing terminals to beconnected to the terminal groups and supplying the electrode groups withsignals through the terminals and also equipped with common signal lineswhich are commonly connected to the driver circuits and driver signallines which are to outputs from the driver circuits and are connected tothe electrode groups on the insulating substrate, the method includingthe step of mounting the flexible circuit boards on the insulatingsubstrate in such a manner as to be arranged close to adjacent flexiblecircuit boards; the step of forming connection terminals in regions ofthe insulating substrate that overlap with the vicinity of gaps betweenadjacent flexible circuit boards; and the step of connecting the commonsignal lines on the flexible circuit boards via the connectionterminals.

A first display device of the present invention includes: electrodegroups formed on an insulating substrate; terminal groups formed in thevicinity of at least one side of the insulating substrate in such amanner as to be connected to outside at the electrode ends of theelectrode groups; driver circuits for inputting the signals to theelectrode groups via terminals to be connected to the terminal groupsand the terminals; and a plurality of flexible circuit boards mounted onthe mounted on the insulating substrate, the display device beingcharacterized in that the flexible circuit boards share overlap regionswith adjacent flexible circuit boards.

A second display device of the present invention is characterized inthat, in the first display device, the overlap regions of adjacentflexible circuit boards are formed by mounting the flexible circuitboards either in such a manner that even-numbered flexible circuitboards when counted from one end of the aligned flexible circuit boardsare partly overlaid on odd-numbered flexible circuit boards, or in sucha manner that odd-numbered flexible circuit boards when counted from oneend of the aligned flexible circuit boards are partly overlaid oneven-numbered flexible circuit boards.

A third display device of the present invention is characterized inthat, in the first or second display device, the flexible circuit boardsfurther include driver signal lines which are coupled to outputs fromthe driver circuits and are connected to the electrode groups on theinsulating substrate and common signal lines which are connected betweenthe flexible circuit boards, and that the common signal lines areconnected between adjacent flexible circuit boards through conductivepatterns on the flexible patterns.

A fourth display device of the present invention is characterized inthat, in the third display device, the common signal lines, which areconnected between adjacent flexible circuit boards by the conductivepatterns on the flexible circuit boards, are connected in regions whichare the overlap regions shared by adjacent flexible circuit boards andwhich also overlap with the surface of the insulating substrate that hasthe electrode groups thereon.

A fifth display device of the present invention includes; electrodegroups formed on an insulating substrate; terminal groups formed in thevicinity of at least one side of the insulating substrate in such amanner as to be connected to outside at the electrode ends of theelectrode groups; and a plurality of flexible circuit boards equippedwith driver circuits containing terminals to be connected to theterminal groups and inputting signals to the electrode groups via theterminals and also equipped with common signal lines which are commonlyconnected between adjacent flexible circuit boards and driver signallines which are outputted from the driver circuits and are connected tothe electrode groups on the insulating substrate, the flexible circuitboards being mounted on the insulating substrate, the display devicebeing characterized in that the flexible circuit boards are mounted onthe insulating substrate in such a manner as to be arranged close toadjacent flexible circuit boards, and that the common signal lines onthe flexible circuit boards are connected via connection terminalsformed in the vicinity of gaps between adjacent flexible circuit boardsand on the insulating substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the liquid crystal display panel inEmbodiment 1 of the present invention.

FIG. 2 is a magnified view of mounted portion A of the flexible circuitboards in FIG. 1.

FIG. 3( a) is a cross sectional view taken along the line B-B of FIG. 2,FIG. 3( b) is a cross sectional view taken along the line C-C of FIG. 2,and FIG. 3( c) is a cross sectional view of the terminal portions of theflexible circuit boards.

FIG. 4 is a plan view of the mounted portion of the flexible circuitboards in Embodiment 2 of the present invention.

FIG. 5 is a cross sectional view taken along the line D-D in FIG. 4.

FIG. 6 is a plan view of the mounted portion of the flexible 10 circuitboards in Embodiment 3 of the present invention.

FIG. 7 (a) is a cross sectional view taken along the line E-E of

FIG. 6, and FIG. 7(b) is a cross sectional view taken along the line F-Fof FIG. 6.

FIG. 8 is a plan view of the mounted portion of the flexible circuitboards in Embodiment 4 of the present invention.

FIG. 9( a) is a cross sectional view taken along the line G-G of FIG. 8,and FIG. 9( b) is a cross sectional view taken along the line H-H ofFIG. 8.

FIG. 10 is a plan view of the mounted portion of the flexible 20 circuitboards in Embodiment 5 of the present invention.

FIG. 11 is a view for explaining the method of mounting flexible circuitboards in the conventional liquid crystal display device.

DETAILED DESCRIPTION Embodiment 1

A first embodiment of the present invention will be described asfollows, based on FIGS. 1 to 3. FIG. 1 is a perspective view of theliquid crystal display panel in the first embodiment of the presentinvention; FIG. 2 is a an enlarged of mounted portion A of the flexiblecircuit boards in FIG. 1; FIG. 3( a) is a cross sectional view takenalong the line B-B of FIG. 2; FIG. 3( b) is a cross sectional view takenalong the line C-C of FIG. 2; and FIG. 3( c) is a cross sectional viewof the terminal portion of the flexible circuit boards.

In FIGS. 1 through 3, there are an insulating substrate 1 made of aglass substrate or the like; a counter substrate 2; a liquid crystaldisplay panel 3; flexible circuit boards 4 made of a film or the like;driver circuits 5; a wiring pattern 6 which is electrode groups on theinsulating substrate 1; driver signal lines 7 which are coupled tooutputs from the driver circuits and coupled to inputs to the liquidcrystal display panel; common signal lines 8 including a start signaland respective power supply line or the like, which are commonlyconnected between the driver circuits; connection regions 9 between theflexible circuit boards and the insulating substrate; connection portion10 between the common signal lines; overlap regions 11 shared by theadjacent flexible circuit boards; fixing portions 12 between adjacentflexible circuit boards; connection terminals 13 of the signal linesformed on the flexible circuit boards; connection terminals 14 of thesignal lines formed on the insulating substrate; connection terminals 15of the common signal lines formed on the rear side of the flexiblecircuit boards; connection terminals 16 of the common signal linesformed on the front side of the flexible circuit boards; a conductivematerial 17; and through holes 18.

As shown in FIG. 1, in order to drive the liquid crystal display panel 3containing a display material such as liquid crystal between theinsulating substrate 1 and the counter substrate 2, the flexible circuitboards 4 having the driver circuits 5 thereon are mounted in thevicinity of at least one peripheral side of the insulating substrate 1.

FIG. 2 is an enlarged view of mounted portion A of the flexible 5circuit boards 4 mounted on the insulating substrate 1 of the liquidcrystal display panel 3 of FIG. 1. As shown in FIG. 2 the flexiblecircuit boards are mounted in such a manner that they are connected withthe electrode terminal portions 14 of the wiring patterns 6 which arethe electrode groups formed on the insulating substrate at theconnection regions 9 between the flexible circuit boards and theinsulating substrate, and that the flexible circuit boards share theoverlap regions 11 with adjacent flexible circuit boards. Such mountingof the flexible circuit boards with the overlap regions 11 betweenadjacent flexible circuit boards achieves high density packaging.

In the present embodiment as shown in FIG. 2 the common signal lines aredirectly connected between adjacent flexible circuit boards in theconnection portion 10 of the common signal lines, which are the overlapregions between adjacent flexible circuit board and are also the overlapregions between the flexible circuit boards and the side of theinsulating substrate that has the wiring patterns 6 thereon as theelectrode groups.

FIGS. 3( a) and 3(b) show cross sectional views taken along the line B-Band the line C-C, respectively, of the connection regions. Theconnection terminals 14 of the driver signal lines on the insulatingsubstrate, which are formed at the end portions of the wiring patterns 6as the electrode groups on the insulating substrate, are connected withthe connection terminals 13 formed on the flexible circuit boards 4 viathe conductive material 17 such as an ACF. In addition, the connectionterminals 15 of the common signal lines formed on the rear sides of theflexible circuit boards 4 are connected with the connection terminals 16of the common signal lines formed on the front sides of the flexiblecircuit boards via the conductive material 17 such as an ACF at regionswhich are the overlap regions 11 shared by adjacent flexible circuitboards 4 and are also the overlap regions 10 between the flexiblecircuit boards 4 and the surface of the insulating substrate on whichthe wiring patterns 6 are formed as the electrode groups. In this case,the patterns 8 for the common signal lines and the patterns 7 for thedriver signal lines on the flexible circuit boards can be formed oneither the front side or the rear side of the flexible circuit boards.And when the patterns for the common signal lines 8 are on the sideopposite to the connection terminals formed on the flexible circuitboards, as shown in FIG. 3( c), through holes 18 are provided on theterminal regions 15 on the substrate so as to connect the patterns 8 forthe common signal lines to the connection terminals 15.

The aforementioned structure achieves high density packaging, and moresecured connections because the common signal lines 8 are directlyconnected between adjacent flexible circuit boards 4 at only one sitewithout a wiring pattern on the insulating substrate 1 or a wiringpattern on the PCB. In addition, in the present embodiment there is theinsulating substrate 1 on the rear side of the connection portions 10between adjacent flexible circuit boards 4. This enables the connectionterminals 16, 15 formed on the front and rear sides of the flexiblecircuit boards to be connected more securely via the conductive material17 such as an ACF hardened by thermo-compression bonding.

When the flexible circuit boards 4 are mounted on the insulatingsubstrate 1, odd-numbered (the first, third, fifth . . . ) flexiblecircuit boards counted from an end of the aligned flexible circuitboards are first mounted on the insulating substrate 1, and theneven-numbered (the second, fourth, sixth . . . ) flexible circuit boardsare mounted. Alternatively, even-numbered (the second, fourth, sixth . .. ) flexible circuit boards counted from an end of the aligned flexiblecircuit boards can be first mounted, and then odd-numbered (the first,third, fifth . . . ) flexible circuit boards can be mounted.

When such mounting is performed, in the case where the odd-numberedflexible circuit boards counted from the left end of the alignedflexible circuit boards shown in FIGS. 3 (a) and 3 (b) are mounted firstand then even-numbered ones are mounted, the connection terminals 15 atthe right and left ends of the second flexible circuit board are botharranged on the top surfaces of adjacent flexible circuit boards. Suchmounting improves workability in replacing a flexible circuit boardhaving a defective driver circuit or a defective wiring pattern with agood one after being installed as a display device, when compared withthe case where flexible circuit boards are mounted in the order in whichthey are aligned.

There are cases where, after being mounted on the insulating substrate1, the flexible circuit boards 4 are bent to the rear side that isopposite to the side having the electrode groups thereon, in order toreduce the frame area of the display device. Workability in the bendingoperation can be improved by applying an adhesive agent to the fixingportion regions 12 which are between adjacent flexible circuit boards ofFIG. 2 in the most appropriate time of the same time as, before, orafter the mounting of the flexible circuit boards. The fixing portions12 are each provided at one site only near the other ends of the overlapregions 11 in the flexible circuit boards 4 that are opposite to theconnection regions between the flexible circuit boards and theinsulating substrate 1; however, the fixing portions 12 can be providedin several sites at predetermined intervals within the number not tocause inconvenience in the bending operation of the flexible circuitboards.

In the present embodiment, as a method of introducing the common signallines 8 into the plural flexible circuit boards 4 from outside, it ispossible to provide terminals to, e.g. the right-end flexible circuitboard of the plural flexible circuit boards in FIG. 1 and otherterminals to the positions on the insulating substrate 1 whichcorrespond to the terminals, thereby introducing the common signal lines8 through these terminals and the patterns on the insulating substrate.

Alternatively, common signal lines 8 that may bypass the driver circuits5 can be provided between the flexible circuit boards 4 and be connectedby using the connection units 10 thereof.

Embodiment 2

A second embodiment of the present invention will be described asfollows based on FIGS. 4 and 5. FIG. 4 is a plan view of the mountedportion of the flexible circuit boards 4 in the second embodiment of thepresent invention, and FIG. 5 is a cross sectional view taken along theline D-D of FIG. 4. In FIGS. 4 and 5, the same components as those inFIGS. 1 to 3 are referred to with the same reference symbols and thefollowing description will be focused on differences between FIGS. 1 to3 and FIG. 4 to 5. In FIGS. 4 and 5, there are connection terminals 19of the common signal lines 8 formed on the insulating substrate 1. Thepresent embodiment differs from the first embodiment in that adjacentflexible circuit boards 4 do not have overlap regions therebetween, andthat the insulating substrate 1 has the connection terminals 19 thereonin order to connect the common signal lines 8 between adjacent flexiblecircuit boards, thereby connecting the driver circuits 5. The connectionterminals 19 of the common signal lines 8 formed on the insulatingsubstrate 1 can be formed at the same time as patterning of the wiringpatterns 6 on the insulating substrate, and can be laid in the positionscorresponding to the connection terminals 16 of the common signal linesformed on the flexible circuit boards.

The aforementioned structure reveals the same effects as in the firstembodiment, and causes no inconvenience in the operation to bend theflexible circuit boards to the rear side of the insulating substrate 1,because the flexible circuit boards 4 are mounted at appropriateintervals not to overlap with adjacent flexible circuit boards. By thismounting, higher density packaging than in the conventional art isattained. In addition, all the flexible circuit boards can be mountedconcurrently.

Embodiment 3

A third embodiment of the present invention will be describedhereinafter based on FIGS. 6 and 7. FIG. 6 is a plan view of the mountedportion of the flexible circuit boards 4 in the third embodiment of thepresent invention, and FIGS. 7( a), 7(b) are cross sectional views takenalong the line E-E and the line F-F of FIG. 6, respectively. In FIGS. 6and 7, the same components as those in FIGS. 1 to 5 are referred to withthe same reference symbols and the following description will be focusedon differences between FIGS. 1 to 5 and FIGS. 6 to 7. Although thepresent embodiment has flexible circuit boards that share overlapregions with adjacent flexible circuit boards 4, it differs from thefirst embodiment in that the common signal lines 8 for connecting thedriver circuits 5 directly connect the common signal lines 8 on theflexible circuit boards in regions which are the overlap regions 11shared by adjacent flexible circuit boards 4 and which do not overlapwith the side of the insulating substrate 1 that has the electrodegroups thereon. The aforementioned structure reveals the same effects asin the first embodiment, and makes it possible to wire the common signallines 8 for connecting the driver circuits 5 with minimum run lengths,thereby suppressing the occurrence of a wiring delay in the commonsignal lines. In the present embodiment too, as in the first embodiment,the common signal lines and the driver signal lines on the flexiblecircuit boards can be formed on either the front side or the rear sideof the flexible circuit boards. Also as in the first embodiment, whenthe flexible circuit boards 4 are folded to the side of the insulatingsubstrate that is opposite to the side having the electrode groupsthereon, workability can be improved by applying an adhesive agent ontoe.g. the contact regions 12.

Embodiment 4

A fourth embodiment of the present invention will be describedhereinafter based on FIGS. 8 and 9. FIG. 8 is a plan view of the mountedportion of the flexible circuit boards 4 in the fourth embodiment of thepresent invention, and FIGS. 9( a) and 9(b) are cross sectional viewstaken along the line G-G and the line H-H of FIG. 8, respectively. InFIGS. 8 and 9, the same components as those in FIGS. 1 to 7 are referredto with the same reference symbols and the following description will befocused on differences between FIGS. 1 to 7 and FIGS. 8 to 9. In FIGS. 8and 9, there are common signal lines 20 which are formed on the sideopposite to the driver signal lines 6 on the flexible circuit boards 4to be entered to the liquid crystal display panel, and through holes 18which alternately connect the common wirings 8 on the front and rearsides of the flexible circuit boards with the common signal lines 20,and the connection terminals 16 of the common signal lines with thecommon signal lines 20. In the present embodiment, as in the thirdembodiment, adjacent flexible circuit boards 4 share overlap regionseach other and the common signal lines 8 for connecting the drivercircuits 5 are directly connected in regions which are in the overlapregions of adjacent flexible circuit boards and do not overlap with theinsulating substrate. On the other hand, the common signal lines 20 onthe flexible circuit boards 4 are formed on the side (the rear side inFIGS. 8 and 9) opposite to the side having the driver signal lines 7 tobe entered to the liquid crystal display panel, and the common signallines 20 and the driver signal lines 7 are patterned on both sides insuch a manner as to cross each other via the flexible circuit boards 4.

The aforementioned structure reveals the same effects as in the thirdembodiment and expands the area for the connection terminals 15 and 16on adjacent flexible circuit boards, thereby further improving theconnection reliability. Also as in the first embodiment, when theflexible circuit boards 4 are folded to the side of the insulatingsubstrate that is opposite to the side having the electrode groupsthereon, workability can be improved by applying an adhesive agent ontothe fixing portions 12 or the like. The present embodiment shows thecase where the 5 driver signal lines 7 and the common signal lines 8 areformed on the front side of the flexible circuit boards, whereas thecommon signal lines 20 crossing the driver signal lines 7 via theflexible circuit boards are formed on the rear side of the flexiblecircuit boards; however, the opposite case would have the same effects.

Embodiment 5

A fifth embodiment of the present invention will be described as followsbased on FIG. 10. FIG. 10 is a plan view of the mounted portion of theflexible circuit boards 4 in the fifth embodiment of the presentinvention. In FIG. 10, the same components as those in FIGS. 1 to 9 arereferred to with the same reference symbols and the followingdescription will be focused on differences between FIGS. 1 to 9 and FIG.10. In the present embodiment, unlike in the fourth embodiment, thecommon signal lines 20, which are arranged on the side opposite to theside having the input signal lines formed on the flexible circuit boardsto be entered to the liquid crystal display panel in the fourthembodiment, are formed on regions the other side of the connectionregions between the flexible circuit boards and the insulating substratewhen viewed from the driver circuits.

The aforementioned structure reveals the same effects as in the fourthembodiment. In the present embodiment when the flexible circuit boards 4are folded to the side of the insulating substrate that is opposite tothe side having the electrode groups thereon, as shown in FIG. 10 theworkability can be improved by setting the contact regions 12 to thevicinity of the center of the overlap regions shared by adjacentflexible circuit boards and applying an adhesive agent thereto. Unlikein the fourth embodiment, the common signal lines 20 on the flexiblecircuit boards are arranged in positions not crossing the driver signallines 7 to be entered to the display device, which makes it possible toprevent the occurrence of a short circuit between these wirings. Thepresent embodiment also shows, as in the fourth embodiment, the casewhere the driver signal lines 7 and the common signal lines 8 are formedon the front side of the flexible circuit boards, whereas the commonsignal lines 20, which are formed in regions on the other side of theconnection regions between the flexible circuit boards and theinsulating substrate when viewed from the driver circuits 5, arearranged on the rear side of the flexible circuit boards; however, theopposite case would have the same effects.

The aforementioned first to fifth embodiments have described methods ofmounting flexible circuit boards equipped with driver circuits fordriving a liquid crystal display device. These embodiments have the sameeffects when applied to any kind of flexible circuit board containingdriver circuits which supply signals to any type of wiring on theinsulating substrate, such as scanning lines or image signal lines,which contributes to display.

The first method of mounting flexible circuit boards of the presentinvention comprises: electrode groups formed on an insulating substrate;terminal groups formed in the vicinity of at least one side of theinsulating substrate in such a manner as to be connected to outside atthe electrode ends of the electrode groups; and a plurality of flexiblecircuit boards equipped with driver circuits containing terminals to beconnected to the terminal groups and supplying the electrode groups withsignals through the terminals, the method comprising the step ofmounting the flexible circuit boards on the insulating substrate in amanner that the flexible circuit boards share overlap regions withadjacent flexible circuit boards. This feature can offer a displaydevice with high density packaging.

The second method of mounting flexible circuit boards of the presentinvention is, in the first method of mounting flexible circuit boards,the step of mounting the flexible circuit boards on the insulatingsubstrate in such a manner that the flexible circuit boards shareoverlap regions with adjacent flexible circuit boards comprises eitherthe step of first mounting odd-numbered flexible circuit boards whencounted from one end of the aligned flexible circuit boards, and thenmounting even-numbered flexible circuit boards or the step of firstmounting even-numbered flexible circuit boards when counted from one endof the aligned flexible circuit boards, and then mounting odd-numberedflexible circuit boards. This feature can offer a display device capableof facilitating the operation to replace a defective flexible circuitboard with a good one.

The third method of mounting flexible circuit boards of the presentinvention is characterized that, in the first or second method ofmounting flexible circuit boards, the flexible circuit boards furtherinclude driver signal lines which are outputted from the driver circuitsand are connected to the electrode groups on the insulating substrate,and common signal lines which are connected between the flexible circuitboards, the method further comprising the step of connecting the commonsignal lines between adjacent flexible circuit boards through conductivepatterns on the flexible circuit boards. This feature can offer adisplay device with high connection reliability. The fourth method ofmounting flexible circuit boards of the present invention ischaracterized that, in the third method of mounting flexible circuitboards, the step of mounting the flexible circuit boards on theinsulating substrate in such a manner that the flexible circuit boardsshare overlap regions with adjacent flexible circuit boards furthercomprises the step of connecting the common signal lines in regionswhere adjacent flexible circuit boards overlap each other and which alsooverlap with the surface of the insulating substrate that has theelectrode groups thereon. This feature can offer a display device withhigher connection reliability.

The fifth method of mounting flexible circuit boards of the presentinvention comprises: electrode groups formed on an insulating substrate;terminal groups formed in the vicinity of at least one side of theinsulating substrate in such a manner as to be connected to outside atthe electrode ends of the electrode groups; and a plurality of flexiblecircuit boards equipped with driver circuits containing terminals to beconnected to the terminal groups and supplying the electrode groups withsignals through the terminals and also equipped with common signal lineswhich are commonly connected to the driver circuits and driver signallines which are outputted from the driver circuits and are connected tothe electrode groups on the insulating substrate, the method comprisingthe step of mounting the flexible circuit boards on the insulatingsubstrate in such a manner as to be arranged close to adjacent flexiblecircuit boards; the step of forming connection terminals in regions ofthe insulating substrate that overlap with the vicinity of gaps betweenadjacent flexible circuit boards; and the step of connecting the commonsignal lines on the flexible circuit boards via the connectionterminals. This feature can offer a display device with high connectionreliability and high density packaging.

The first display device of the present invention comprises: electrodegroups formed on an insulating substrate; terminal groups formed in thevicinity of at least one side of the insulating substrate in such amanner as to be connected to outside at the electrode ends of theelectrode groups; and a plurality of flexible circuit boards equippedwith driver circuits containing terminals to be connected to theterminal groups and supplying the electrode groups with signals throughthe terminals, the flexible circuit boards being mounted on theinsulating substrate, the display device being characterized in that theflexible circuit boards share overlap regions with adjacent flexiblecircuit boards. This feature can achieve high density packaging.

The second display device of the present invention is characterized inthat, in the first display device, the overlap regions of adjacentflexible circuit boards are formed by mounting the flexible circuitboards either in a manner that even-numbered flexible circuit boardswhen counted from one end of the aligned flexible circuit boards arepartly overlaid on odd-numbered flexible circuit boards, or in such amanner that odd-numbered flexible circuit boards when counted from oneend of the aligned flexible circuit boards are partly overlaid oneven-numbered flexible circuit boards. This feature can facilitate theoperation to replace a defective flexible circuit board with a good one.

The third display device of the present invention is characterized inthat, in the first or second display device, the flexible circuit boardsfurther comprise driver signal lines which are outputted from the drivercircuits and are connected to the electrode groups on the insulatingsubstrate and common signal lines which are connected between theflexible circuit boards, and that the common signal lines are connectedbetween adjacent flexible circuit boards through conductive patterns onthe flexible patterns. This feature can improve connection reliability.

The fourth display device of the present invention is characterized inthat, in the third display device, the common signal lines, which aredirectly connected between adjacent flexible circuit boards by theconductive patterns on the flexible circuit boards, are connected inregions which are the overlap regions shared by adjacent flexiblecircuit boards and which also overlap with the surface of the insulatingsubstrate that has the electrode groups thereon. This feature canfurther improve connection reliability.

The fifth display device of the present invention comprises electrodegroups formed on an insulating substrate; terminal groups formed in thevicinity of at least one side of the insulating substrate in such amanner as to be connected to outside at the electrode ends of theelectrode groups; and a plurality of flexible circuit boards equippedwith driver circuits containing terminals to be connected to theterminal groups and supplying the electrode groups with signals throughthe terminals and also equipped with common signal lines which arecommonly connected between adjacent flexible circuit boards and driversignal lines which are outputted from the driver circuits and areconnected to the electrode groups on the insulating substrate, theflexible circuit boards being mounted on the insulating substrate, thedisplay device being characterized in that the flexible circuit boardsare mounted on the insulating substrate in such a manner as to bearranged close to adjacent flexible circuit boards, and that the commonsignal lines on the flexible circuit boards are connected via connectionterminals formed in the vicinity of gaps between adjacent flexiblecircuit boards and on the insulating substrate. This feature can improveconnection reliability and achieve high density packaging.

1. Method of mounting flexible circuit boards including: electrodegroups formed on an insulating substrate; terminal groups formed in thevicinity of at least one side of the insulating substrate in such amanner as to be connected to outside at the electrode ends of theelectrode groups; and terminals to be connected to the terminal groups;and a plurality of flexible circuit boards equipped with driver circuitsinputting signals to the electrode groups via the terminals, whereinsaid method includes the step of mounting the flexible circuit boards onthe insulating substrate in such a manner that the flexible circuitboards share overlap regions and have physical contacts in said overlapregions with adjacent flexible circuit boards. 2-5. (canceled)
 6. Adisplay device comprising: electrode groups formed on an insulatingsubstrate, terminal groups formed in the vicinity of at least one sideof the insulating substrate in such a manner as to be connected tooutside at the electrode ends of the electrode groups, driver circuitsfor inputting the signals to the electrode groups via terminals to beconnected to the terminal groups and the terminals, and a plurality offlexible circuit boards mounted on the mounted on the insulatingsubstrate, wherein a part of linearly extended sides of any one of saidflexible circuit boards share overlap in a region where said one of saidone of said flexible circuit boards is overlapped with said insulatingsubstrate and another region where said one of said flexible circuitboards is not overlapped with said insulating substrate with adjacentflexible circuit boards which are adjacent to said one of said flexiblecircuit boards. 7-10. (canceled)
 11. The method of claim 1, wherein saidflexible circuit boards have common signal lines.
 12. The device ofclaim 6, wherein said flexible circuit boards have common signal lines.